Machine for dry-cleaning articles

ABSTRACT

The machine ( 1 ) for dry-cleaning and drying articles such as clothes, household linen, towels, curtains and the like comprises a rotary drum ( 2 ) which contains the articles, a closed circuit ( 3 ) for circulation of the air used for drying the articles and a refrigeration system ( 14 ) for the treatment of said drying air.

TECHNICAL FIELD

The present invention relates to a machine for dry-cleaning articlessuch as clothes, household linen, towels, curtains and the like.

In particular, the present invention relates to the drying circuit ofsuch a machine which is also designed to simultaneously perform anaction, also known as abatement, removing from the articles the solventused for dry-cleaning.

BACKGROUND ART

There are prior art dry-cleaning machines comprising a drying andabatement circuit which, also integrating the drum in which the articlesare treated, comprise a fan for circulation of the air, a condenser forcondensing the solvent contained in the air and a heating element forheating the air before reintroducing it into the drum in which, thanksto its high temperature, it can remove the dry-cleaning solvent from thearticles by vaporisation.

The condenser usually consists of the evaporator of a refrigerationcircuit whilst the condenser of the same circuit forms theabove-mentioned air heating element.

In order that the air circulating in the drying circuit reaches atemperature value sufficient to guarantee an effective drying action andabatement of the solvent from the articles, additional heating elementsare used, positioned in series relative to the refrigeration systemcondenser.

Such additional heating elements are usually of the type with anelectric heating element or steam powered.

The presence of the heating elements is not without disadvantages.Irrespective of the specific type selected, it involves considerableenergy absorption with consequent increases in the costs perdry-cleaning cycle.

DISCLOSURE OF THE INVENTION

The aim of the present invention is to overcome the above-mentioneddisadvantage with a machine for dry-cleaning articles such as clothes,household linen, towels, curtains and the like, which allows theeffective and economical execution of dry-cleaning and drying cycles forsaid articles, the machine being simple and economical to make and easyand practical to use.

The technical features of the present invention, in accordance with theabove aims, are clear from the content of the claims herein, inparticular claim 1, and from any of the claims directly or indirectlydependent on claim 1.

The present invention also relates to a method for dry-cleaningarticles.

The method according to the present invention is described in claim 10and any of the claims directly or indirectly dependent on claim 10.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present invention are more apparent in thedetailed description which follows, with reference to the accompanyingdrawings which illustrate preferred, non-limiting embodiments of theinvention, in which:

FIG. 1 is a schematic view of a preferred embodiment of the machine fordry-cleaning articles in accordance with the present invention;

FIG. 2 is a schematic view of an alternative embodiment of the machineof FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIG. 1, the numeral 1 denotes as a whole the machinefor dry-cleaning articles in accordance with the present invention.

The machine 1 comprises a drum 2 or container in which the articles tobe dry-cleaned are inserted.

The drum 2 rotates, driven by motor elements of the substantially knowntype not described or illustrated, about an axis of rotation A.

The machine 1 comprises a closed circuit 3 for the circulation of airfor drying the articles contained in the drum 2 which are notillustrated. As FIG. 1 clearly shows, the drum 2 is positioned in theclosed circuit 3.

At the drum 2 outfeed, according to the direction of the air flowindicated by the arrows FA illustrated in FIG. 1, the closed circuit 3comprises a filtering zone 4 designed to catch any materials carried bythe air flow, such as hairs and threads detached from the articlesduring drying.

Downstream of the filtering zone 4, on the circuit 3 there is a fan 5for moving the air. Downstream of the fan 5, again according to thedirection of the arrows FA, the circuit 3 comprises an ascending duct 6which conveys the air to a condensation battery 7 and to a heatingelement 8.

The condensation battery 7 is designed to condense the solvent in vapourform transported by the flow of drying air, whilst the heating element 8is designed to raise the temperature of the air circulating along thecircuit 3.

At the condensation battery 7 there is a zone 9 for collection of thesolvent condensed, which is fed to a collection tank 12 through arecovery duct 10 and a respective filter 11.

Using inlet and drainage means of the known type and not illustrated,the solvent is sent to and drained from the drum 2 respectively from andto the collection tank 12.

Downstream of the heating element 8 the circuit 3 comprises a descendingduct 13 which introduces the heated air into the drum 2, thus closingthe circuit 3.

As illustrated in FIG. 1, the machine 1 comprises a refrigeration system14 along which a respective refrigerant flows.

The refrigeration system 14 comprises, positioned one after another, arefrigerant compressor 15, a first condenser 16, a refrigerant receiver17, a filter 18 for catching any impurities, a refrigerant expansionvalve 19 and a first evaporator 20 for the refrigerant.

The above-mentioned elements of which the refrigeration system 14consists are in fluid connection with one another by means of aplurality of pipes having numerous on-off and check valves. Both thepipes and the valves are described in detail below.

In FIG. 1 the above-mentioned pipes are labelled from T1 to T13, whilstthe on-off valves are labelled V1 to V7. The check valves are labelled21.

As is explained in more detail below, the first evaporator 20 and thefirst condenser 16 of the refrigeration system 14 are integrated in theclosed circuit 3 to perform a heat exchange with the air circulating init, and they respectively form the heating element 8 and thecondensation battery 7. The first condenser 16 and the first evaporator20 are therefore two heat exchangers which, in the circuit 3, formrespective means for the treatment of the air circulating in the circuit3.

The refrigeration system 14 also comprises an auxiliary heat exchanger22 which is positioned outside the circuit 3, so that it does notperform any heat exchange with the air circulating in the circuit 3.

The auxiliary heat exchanger 22 comprises a respective fan, notillustrated, designed to increase the efficiency of the heat exchange byestablishing a forced air flow.

The machine 1 comprises a computerised control and operating unit forcontrolling the opening and closing of the on-off valves according tothe different machine 1 operating steps.

Along the air circulation circuit 3, downstream of the fan 5, there is afirst element 23 for detecting the air temperature, hereinafterindicated simply as the sensor 23.

In practice, after inserting the articles to be dry-cleaned in the drum2, a dry-cleaning solvent is introduced into the drum 2.

There follows a step in which the drum 2 is made to rotate about itsaxis A so as to distribute the solvent effectively on the articles to bedry-cleaned.

Once the dry-cleaning operations are considered complete, the articlesmust be dried to remove the liquid solvent used for dry-cleaning fromthem.

To dry the solvent from the articles, the articles are struck by a flowof hot air.

Therefore, said air must be treated, both to heat it and to remove fromit the solvent which, in the form of vapour, is removed from thearticles.

The air treatment, that is to say, basically its heating and the removalfrom it, by condensation, of the vaporised solvent, involves specialoperating steps by the refrigeration system 14 described above.

In particular, a first step of heating the air from an ambienttemperature to to a predetermined temperature t₁, is carried out byactivating the passage of the refrigerant through the first condenser 16forming the circuit 3 heating element 8, but without allowing therefrigerant to circulate through the first evaporator 20 forming thecircuit 3 condensation battery 7. In this way, the air circulating inthe circuit 3 is heated after the heat exchange which takes place at theheating element 8 and, therefore, its temperature is raised.

A second step with simultaneous heating of the air and condensing of thevapour contained in it takes place starting from the temperature t₁until the air reaches a temperature t₂ higher than t₁.

In this second step the refrigerant passes through both the firstcondenser 16 to heat the air, and through the first evaporator 20 tocondense the solvent contained in the air in vapour form.

The first step of only heating the air is therefore a transient step inwhich the air is heated from the temperature t₀ to the temperature t₁.

During said first transient step of machine 1 starting, the refrigerantcoming out of the compressor 15 flows along the pipe T1 as far as thepoint P1 of intersection with the pipes T2 and T3. From the point P1,with the valve V4 open and the valve V5 closed, the refrigerant flows tothe first condenser 16, in the direction indicated by the arrow F1.

As it passes through the first condenser 16, the refrigerant iscondensed, transferring heat to the air circulating in the closedcircuit 3, therefore said air is heated.

As it comes out of the first condenser 16, the refrigerant flows alongthe pipe T4 according to the direction indicated by the arrow F2 untilit reaches the point P2 of intersection of the pipe T4 with the pipes T5and T6.

With the valve V2 open and the valve V3 closed, the refrigerant flowsalong the pipe T5 according to the direction indicated by the arrow F3and reaches the receiver 17, passing through the point of intersectionP3 towards which there also converges a pipe T6′ from the auxiliary heatexchanger 22.

A check valve 21 is advantageously positioned on the pipe T5 close tothe point of intersection P3.

The refrigerant receiver 17 is of the known type and therefore itsfunctions in the refrigeration system 14 are not described in detail.

The refrigerant coming out of the receiver 17 flows along the pipe T7according to the direction indicated by the arrow F4 and reaches theexpansion valve 19. Positioned along the pipe T7 there is a filter 18for filtering the refrigerant coming out of the receiver 17, catchingany impurities present in it.

The refrigerant which expands in the expansion valve 19, with the on-offvalve V1 closed and the valve V6 open, passes through the point P5 ofintersection between the pipes T8 and T9 and, flowing along the latteraccording to the direction indicated by the arrow F5, reaches theauxiliary heat exchanger 22. At the latter, the refrigerant performs aheat exchange with the outside air, absorbing heat from it andevaporating.

Therefore, during the present transient step of machine 1 starting theauxiliary heat exchanger 22 forms a second evaporator, alternative tothe first evaporator 20. In said transient step, the refrigerant doesnot flow through the first evaporator 20.

During the transient step, the refrigerant comes out of the auxiliaryheat exchanger 22 through the pipe T10 along which it flows according tothe direction indicated by the arrow F6 to the point P4 of intersectionwith the pipes T3, T6 and T11.

With the valves V3 and V5 closed and the valve V7 open, the refrigerantreaches the point P6 of intersection between the pipes T11, T12 and T13,flowing along the pipe T11 according to the direction indicated by thearrow F7. Therefore, passing through the point P6, the refrigerant flowsalong the pipe T12 according to the direction indicated by the arrow F8until it goes back into the compressor 15.

At the same time as the refrigeration system 14 transient step takesplace, the air circulating in the closed circuit 3 is heated by heatexchange with the heating element 8 consisting of the refrigerationsystem 14 first condenser 16.

The transient cycle described above is repeated until the sensor 23located downstream of the fan 5 detects air temperature values lowerthan a predetermined value t₂, for example between 30° C. and 40° C.Reaching the temperature value t₂ confirms the end of the transient stepand the start of a refrigeration system 14 regular operation step.

In particular, when the predetermined temperature t₂ is reached, thecomputerised control and operating unit referred to but not illustratedissues the command to close the valve V6 and simultaneously open thevalve V1. In this way, the refrigerant which expanded in the expansionvalve 19 flows along the pipe T8 according to the direction indicated bythe arrow F9, reaching the first evaporator 20 integrated in the dryingcircuit 3.

In practice, whilst in the previous transient step the refrigerant wasdiverted at the point P5 towards the auxiliary heat exchanger 22, now,in the regular operation step, the refrigerant is directed towards thefirst evaporator 20.

At the first evaporator 20, the refrigerant evaporates, absorbing heatfrom the moist hot air circulating in the closed circuit 3 and socausing the vaporised solvent present in said hot air to condense.

Most of the thermal power removed from the air at the first evaporator20 is the latent heat of vaporisation.

The refrigerant evaporated in the first evaporator 20 then flows alongthe pipe T13, according to the direction indicated by the arrow F10,towards the point P6 of intersection and from there, because the on-offvalve V7 is closed, again into the compressor 15 through the pipe T12.

Machine 1 operation involves transient safety steps during which therefrigeration system 14 cycle is subject to transient modificationscompared with its regular operation just described, so as to bringwithin predetermined safety ranges several parameters such as the airtemperature in the circuit 3 or the pressure of the refrigerant in therefrigeration system 14.

In a first transient safety step, starting with normal regularoperation, if the refrigerant coming out of the compressor 15 reaches apressure value greater than a predetermined calibration value p₁ of afirst pressure switch 24, the computerised control and operating unitcloses the valve V4 and, at the same time, opens the valve V5.

In this way, the refrigerant coming out of the compressor 15, havingreached the point P1 of intersection, is diverted along the pipe T3along which it flows according to the direction indicated by the arrowF11 and, having reached the point P4 of intersection, because the valvesV3 and V7 are closed, it flows directly towards the auxiliary heatexchanger 22, through the pipe T10. This time, it flows along the pipeT10 according to the direction indicated by the arrow F12, that is tosay, in the opposite direction to that during the transient startingstep described above.

The simple flowing of the refrigerant along the exchange circuit in theauxiliary heat exchanger 22, usually of the coil type, generates, due tothe pressure losses linked to the circuit, an inevitable reduction inthe pressure of the refrigerant, irrespective of the heat exchange whichtakes place along the circuit and of the consequent condensation.

If the refrigerant reaches an even greater pressure value p2, ofcalibration of a second pressure switch 25, the computerised unitswitches on the respective fan, not illustrated, belonging to theauxiliary heat exchanger 22, so as to make the release of heat to theoutside even more efficient.

Therefore, during the present first transient safety step, the auxiliaryheat exchanger 22 forms a second condenser for the refrigerant,alternative to the first condenser 16.

As it comes out of the auxiliary heat exchanger 22, the refrigerantflows along the pipe T6′ according to the direction indicated by thearrow F13 and is reintroduced into the receiver 17. From the receiver17, the refrigerant again flows through the pipe T7 and from theretowards the expansion valve 19.

The first transient safety step is concluded as soon as the pressureswitch 24 and/or the pressure switch 25 detect refrigerant pressurevalues less than their respective calibration values p₁ and p₂.

A second transient safety step is implemented, starting with normalregular operation, if a second temperature detection element 26 detectsa temperature greater than a predetermined safety value t_(S) for therefrigerant entering the first condenser 16. For example, the value oft_(S) is advantageously approximately 95° C.

In the second transient safety step, if it is detected that therefrigerant has reached the temperature value t_(S), the computerisedcontrol and operating unit, not illustrated, by closing on-off valve V2and simultaneously opening valve V3, diverts the flow coming out of thefirst condenser 16 along the pipe T6 along which it flows according tothe direction indicated by the arrow F13. Having reached the point P4 ofintersection, since both of the valves V5 and V7 are closed, therefrigerant flows directly towards the auxiliary heat exchanger 22,through the pipe T10, along which it flows according to the directionindicated by the arrow F12.

At the auxiliary heat exchanger 22, if necessary even by switching onthe respective fan, not illustrated, the refrigerant transfers heat tothe outside before returning to the receiver 17 and, from there, to theexpansion valve 19.

In this way, the temperature of the refrigerant has been lowered bymaking it perform an additional heat exchange with the outside, notincluded in the normal regular operation cycle of the refrigerationsystem 14.

Therefore, as in the first transient safety step described above, inthis second transient safety step the auxiliary heat exchanger 22 formsa second condenser for the refrigerant, alternative to the firstcondenser 16.

As soon as the temperature of the refrigerant detected by the seconddetection element 26 returns to values lower than the predeterminedvalve t_(S), the second transient safety step is ended and thecomputerised control and operating unit returns the valves V2 and V3 totheir respective configurations adopted during regular operation of therefrigeration system 14, that is to say: valve V2 open and valve V3closed.

The refrigeration system 14 comprises two additional pressure switches:a third safety pressure switch 27, positioned along the pipe T1, and afourth pressure switch 28 for minimum pressure, positioned along thepipe T11, upstream of the compressor 15.

The third safety pressure switch 27 is designed, through thecomputerised control and operating unit with which it is connected, tostop machine 1 operation if the pressure of the refrigerant exceeds apredetermined safety pressure value.

The fourth pressure switch 28 is designed, through the computerisedcontrol and operating unit with which it is connected, to stop machine 1operation if the pressure of the refrigerant is lower than apredetermined pressure value below which the refrigeration system 14could be damaged.

The above-mentioned on-off valves V1, V2, V3, V4, V5; V6, V7, togetherwith the check valves 21, form valve means for the refrigeration system14.

Said valve means, together with the computerised control and operatingunit referred to but not illustrated, form control means for regulatingthe flow of refrigerant in the refrigeration system 14.

FIG. 1 does not illustrate means for introducing the solvent into and/orextracting it from the drum 2, since these are of the substantiallyknown type and are not useful to an understanding of the presentinvention.

By way of example only, it was proven that using BFC 134a gas(commercially also known as Freon R134a) as the refrigerant, partlybecause of its low impact on the ozone, the machine operatingtemperatures, considering to to be ambient temperature, are as follows:

t₁ between 30 and 40° C.,

t_(S) between 90 and 100° C.

Tests have shown optimum machine operation with the air temperature t₁set at around 36° C. and the maximum temperature t_(S) of therefrigerant set at around 95° C.

The value of temperature t₂ is closely linked to the type of articlesbeing dry-cleaned and to the temperatures they can tolerate withoutdeteriorating. An average drying air temperature t₂ able to alloweffective drying of articles is, for example, around 70° C.

Again by way of example, assuming that HFC 134a gas is used as therefrigerant, possible values for the calibration pressures p₁ and p₂ ofthe pressure switches 24 and 25 are, respectively, around 24 Bar and24.5 Bar.

Therefore, advantageously, the present invention allows the treatment ofthe air for drying dry-cleaned articles without the need for thermalpower in addition to that supplied by the refrigeration system normallycoupled to the machine.

With the machine disclosed, the thermal power generated with therefrigeration cycle is sufficient to dry the articles. Tests have shownthat, with the refrigerant indicated above, the air temperature onaverage reaches the value of 70° C. in very short periods of time andabsolutely compatible with the duration of the dry-cleaning cyclescurrently used.

According to the alternative embodiment illustrated in FIG. 2, themachine 1 comprises a circuit 100 for cooling the solvent fed to thedrum 2, the circuit 100 extending from the pipe T7, downstream of thefilter 18 according to the direction indicated by the arrow F4.

The circuit 100 comprises an on-off valve V8, a cooler 101 and, insertedbetween them, an expansion valve 102. The cooler 101 comprises a coilheat exchanger 103 outside which there flows the above-mentioned solventto be sent into the drum 2. FIG. 2 does not illustrate the respectivesolvent feed and extraction ducts to and from the cooler 101, since theyare considered to be of the substantially known type. In practice, bymeans of the on-off valve V8, the refrigerant coming out of the filter18 is diverted to the cooling circuit 100 and expands at the expansionvalve 102.

The refrigerant which expanded in the valve 102 flows along the circuit100, reaching the cooler 101, where it evaporates, absorbing heat fromthe solvent circulating outside the coil heat exchanger 103, thuscausing the solvent to cool. The circuit 100 joins the pipe T12 againand the refrigerant then flows towards the compressor 15.

Use of the solvent cooling circuit 100 disclosed by the alternativeembodiment illustrated in FIG. 2 advantageously allows the temperatureof the solvent to be kept within required values, thus guaranteeing,when necessary, the availability of low temperature solvent, for examplefor dry-cleaning delicate articles.

The invention described above may be modified and adapted in severalways without thereby departing from the scope of the inventive concept.Moreover, all details of the invention may be substituted by technicallyequivalent elements.

1. A machine for dry-cleaning articles such as clothes and the like,comprising: a rotary drum (2) for containing the articles, means forintroducing solvent into and draining it from the drum, a substantiallyclosed circuit (3) for circulation of air for drying the solvent fromthe articles contained in the drum (2), the circuit (3) comprising atleast one fan (5) for moving the air, a first evaporator (20) of arefrigeration system (14) for condensing the solvent contained in theair, and a first condenser (16) belonging to the refrigeration system(14) for heating the air to be reintroduced into the drum (2), themachine being characterised in that the refrigeration system (14)comprises an auxiliary heat exchanger (22), outside the closed circuit(3) for circulation of the air and control means for feeding towards theauxiliary heat exchanger (22), at least for predetermined periods, therefrigerant normally flowing between the first evaporator (20) and thefirst condenser (16).
 2. The machine according to claim 1, characterisedin that the control means comprise valve means (V1, V6) for divertingtowards the auxiliary heat exchanger (22) the refrigerant which normallyflows towards the first evaporator (20) of the refrigeration system(14), the auxiliary heat exchanger (22) forming a second evaporator,alternative to the first evaporator (20).
 3. The machine according toclaim 1, characterised in that the control means comprise valve means(V4, V5) for diverting towards the auxiliary heat exchanger (22) therefrigerant which normally flows towards the first condenser (16) of therefrigeration system (14), the auxiliary heat exchanger (22) forming asecond condenser, alternative to the first condenser (16).
 4. Themachine according to claim 1, characterised in that the control meanscomprise valve means (V2, V3) for diverting towards the auxiliary heatexchanger (22) the refrigerant coming out of the first condenser (16),the auxiliary heat exchanger (22) forming a second condenser, inaddition to the first condenser (16).
 5. The machine according to claim1, characterised in that the auxiliary heat exchanger (22) comprises arespective auxiliary fan designed to increase the efficiency of the heatexchange by means of a forced air flow.
 6. The machine according toclaim 2, characterised in that it comprises a computerised control andoperating unit, the unit controlling the valve means (V1, V2, V3, V4,V5, V6, V7) and the auxiliary fan according to the achievement ofpredetermined temperature and/or pressure values by the refrigerantand/or the air circulating in the closed circuit (3).
 7. The machineaccording to claim 6, characterised in that the computerised control andoperating unit comprises a first element (23) for detecting the airtemperature, positioned along the closed circuit (3).
 8. The machineaccording to claim 6, characterised in that the computerised control andoperating unit comprises at least a second element (26) for detectingthe temperature of the refrigerant.
 9. The machine according to claim 1,characterised in that it comprises a circuit (100) for cooling thesolvent to be fed to the drum (2).
 10. The machine according to claim 9,characterised in that the cooling circuit (100) comprises a heatexchanger (103) along which refrigerant flows.
 11. The machine fordry-cleaning articles such as clothes and the like, in particularaccording to claim 1, comprising: a rotary drum (2) for containing thearticles, a substantially closed circuit (3) for circulation of air fordrying the dry-cleaning solvent from the articles contained in the drum(2), the circuit (3) comprising air treatment means, the machine beingcharacterised in that the air treatment means comprise heat exchangers(16, 20) exclusively of the type along which a refrigerant flows andbelonging to a refrigeration system (14).
 12. A method for dry-cleaningarticles such as clothes and the like, comprising the steps of:introducing a dry-cleaning solvent into a drum (2) for containing thearticles, rotating the drum (2) to distribute the solvent on thearticles, making an air flow circulate along a substantially closedcircuit (3) in which the drum (2) is integrated, treating the air to drythe solvent from the articles, the method being characterised in thatthe air treatment step comprises a step of heating the air from a firsttemperature (t₀) to a second predetermined temperature (t₂) and a stepof condensing the solvent contained in the air, the condensing stepbeing implemented only from when the air has reached a predeterminedintermediate temperature (t₁), between the first and second temperatures(t₀, t₂).
 13. The method according to claim 12, wherein the step ofcondensing the air is implemented by passing the air flow through acondensation battery (7) consisting of a first evaporator (20) of arefrigeration system (14) in which a refrigerant circulates, the methodbeing characterised in that the refrigerant is fed to the firstevaporator (20) only after the air has reached a temperature greaterthan or equal to the predetermined intermediate temperature (t₁). 14.The method according to claim 13, characterised in that during the stepof heating the air from the first temperature (t₀) to the intermediatetemperature (t₁), the refrigerant is fed to an auxiliary heat exchanger(22) outside the closed circuit (3), the auxiliary heat exchanger (22)forming a second evaporator of the refrigeration system (14),alternative to the first evaporator (20).